The present invention relates to a control element for a printed article, in particular for securities or the like, which has, printed on a first side of said article, a first drawing comprising at least a first screen.
Such control elements are known in the prior art and are principally used to prevent the counterfeiting of securities, in particular the reproduction of banknotes. To make this counterfeiting, whether by photo-copying or by the use of a scanner coupled to a color printer, difficult or even impossible, control elements, usually called security elements, have begun to be incorporated into printed securities in addition to the special means already employed, such as for example watermarks in the paper.
This is because the technical advances made in photocopiers and scanners have been such that very effective equipment is now easily accessible to anyone. Thus the security elements themselves have had to be increased and improved as a consequence.